In France there's Bicycode. The sole increase in risk of a bike being visibly tagged vs one that is not is enough to make the baddies pick the other one.

Also there are actually two types of bicycle thiefs: organised groups that load them by the truckload and opportunistic folks that know most locks are trivially broken and just want a cheap ride. You'd be surprised how many times I witnessed guys just carelessly dropping "their" bike once arrived.

[0]: http://www.bicycode.org